function getXMLHttpRequest() {

        var xhr = null;
        if (window.XMLHttpRequest || window.ActiveXObject) {
                if (window.ActiveXObject) {
                        try {
                                xhr = new ActiveXObject("Msxml2.XMLHTTP");
                        } catch(e) {
                                xhr = new ActiveXObject("Microsoft.XMLHTTP");
                        }
                } else {
                        xhr = new XMLHttpRequest();
                }
        } else {
                alert("Votre navigateur ne supporte pas l'objet XMLHTTPRequest...");
                return null;
        }
        return xhr;
}
